Ethers of dextran



Patented June 11, 1940 Grant L. Stahly and Warner W.

Carlson,

Columbus, Ohio, assignors to Commonwealth Engineering Corporation, Wilmington, DeL, a corporation of Delaware NoDrawlng, Application July 29, 1937,

Serial No. 156,427

20 Claims.

This invention relates to the production of polysaccharide materials by the action of various micro-organisms on suitable culture media, and to processes for converting these polysaccharides intotheir ether, mixed ether, ester, mixed ester or mixed ether-ester derivatives.

It is the object of this invention to produce polysaccharide materials by the action of various micro-organisms on suitable culture media and in particular to produce dextran; and to thereafter subject the polysaccharide materials such as dextran to a process of etherification or esterification either while the materials are in the culture media or after separation therefrom so as to produce the 15 newproducts of resinous character such as the so from one another by the fact that on hydrolysis with acids or enzymes, the dextrans yield only dextrose while the levans yield only levulose. As specific examples, Bacillus mesentericus, B. subtilis, B. meyatherium, Pseudomonas prum', Ps. prunicola or Ps. phaseoli may be employed for the production of the levan type of polysaccharide, while Leuconostoc mesenteroides or L. dextranicum may be used for the production of the dextran type. r i r The culture media employed must contain some sucrose; this canbe either refined or crude sucrose, molasses or any similar sucrose containing material. Nitrogen may be added inthe form of commercial peptone, beef extract or other nitrogen containing material. If molasses is used as the sucrose source, nitrogenous compounds in suflicient quantity are present in it so that none need be added. Salts such as dipotassium phosphate and sodium chloride are also added. As 50 a specific example, a typical medium may contain: sucrose, 540%, peptone, 0.1%, dipotassium phosphate 0.2% and sodium chloride 0.1%. The pH of the medium preferably is adjusted to slightly on the alkaline side of neutrality. 55 n The production of the polysaccharide is favored by keeping the reaction of the media slightly alkaline throughout the period of fermentation. This may be acomplished by the periodic addition of alkali to the fermenting media or by using an excess of calcium carbonate in the media. After inoculation the cultures are incubated at the temperature most favorable, to the growth of the micro-organism being used. For one of the preferred forms, Leuconostoc mesenteroides, this temperature is around 25 degrees C. The progress of the fermentation may be followed by periodically removing samples of the fermenting culture media and. precipitating the polysaccharide contained in them by the addition of three to five times their volume of alcohol. The precipitated polysaccharide may then be weighed. When a maximum of polysaccharide has been formed the culture media are ready for the etherification or esterification processes. The length of time necessary for the maximum of polysaccharide to be formed will vary with the organism employed, the temperature of incubation, the concentration of sucrose and other factors.

The polysaccharide may be isolated from the solution by precipitation with alcohol or acetone. Preferably the reaction of the fermented medium is first adjusted to the neutral point to lessen the possibility of hydrolysis of the polysaccharide, and the solution then concentrated under reduced pressure at a temperature of 40 to 50 degrees C. to approximately one-fourth its original volume. The solution is then poured, with stirring, into three to five times its volume of alcohol or acetone. The polysaccharide may be precipitated directly from the fermented culture media by the addition of alcohol or acetone, but it is then necessary to use a considerably larger amount of the precipitating agent.

For the preparation of the ether and ester derivatives of these polysaccharides it is not necessary that they first be isolated from the culture media in which they were formed. Instead the necessary reagents may be added directly to the fermented media, and after completion of the reethers and/or esters of the polysaccharide, the corresponding derivatives of any excess sucrose be desirable since a blending ofthese various derivatives yieldsfla product with a: ran'geoi solubilities. However, in cases ,inwhich. a prodact with the specific properties ofthe polysaccharide derivative alone are desired,-'it is necessary either to separate'the dextrans or-"levans from theculture media before chemical treat;

ment, or else'toremove the undesirable byproducts, from the mixture obtained by the direct treatment of the fermented media by ithe use of specific solvents.

Whether the fermented media are treated directly, or thepolysaccharides first isolated by, alcohol or acetone precipitation, the proportions of the, reactants used in the preparation of the ether derivatives are approximately as follows: one mo] of the polysaccharide, 3.5 mols of the alkyl or aralkyl halide and 4.5 mols of sodium hydroxide. If the polysaccharide was isolated from the medium before the chemical treatment, suificient water must be added to the mixture so as to yield approximately a 10 per cent solution of the sodium hydroxide.

If the fermented culture medium itself is used. the amount of water present should be so regulated by concentration or dilution to again yield approximately a 10 per cent solution of the alkali. After addition of the reagents the mixture is heated for a predetermined time, usually 4 to 6 hours, at a temperature anywhere from 80 to 130 degrees C. This temperature depends on the derivative being prepared.

In general, the higher the temperature and the longer the period of heating the greater will be the number of hydroxyl groups in the polysaccharide which will be substituted by the organic radical of the halide compound used. The tem-- perature and time of heating employed is consequently governed by the type of product desired. The organic halide used may be any member of the aliphatic series such as methyl chloride, ethyl chloride, propyl or isopropyl chloride, butyl chloride or any of its isomers, etc, or any one of the araliphatic series such as benzyl chloride.

The aliphatic derivatives are water soluble, at least as high as the butyl derivative. The benzyl ethers are generally water insoluble. Regardless of the type of organic halide used, increasing the proportion of halide to polysaccharide, running the reaction at a higher temperature and for a longer period of time will generally result in a decreased water solubility for the products obtained.

It is to be understood that the organic halide used may be either the chloride, bromide or iodide derivative. For purposes of economy, the chlorides are generally employed.

At the conclusion of the reaction period excess halide is recovered by any suitable process such as steam distillation. The product is isolated by mechanical means if it is water insoluble or by precipitation if it is water soluble.

The process may be varied by the simultaneous introduction oi two or more organic halide compounds into the reaction mixture, in. which case the product will be a mixed ether; or a particular ether derivative may be prepared-and the product from the reaction then treated with a diiferent organic halide to yield a mixed ether derivative. Again, an ether derivative may be prepared and then further treated with organic aaoavos the preparation of mixed ether-ester derivatives.

Such variations in treatment are, of course, almost without number.

The products in general are to be described as plastic, amorphous masses, either water solu- .bleor", insoluble depending upon the reaction conditions and the particular. halide employed. As an example. the benzyl ether of dextran is a water insoluble material which resists the action of the common organic solvents, while'the butyletherof 'dextran'iswater soluble.

The 'iollowing are examples. of: specific prac tices of our method for the production of new products. It willbeunderstood we do not desire to'be' confined-to the detailed proportions,

temperatures and pressures. although we are reciting hereinafteithose that we have found to be the preterredtemperatures and other conditions.

It will be further understood that u; is comprehended within this process the production of a large number of allied materials.

It will be further understood that'we are illustrating the process and the materials that can be produced by typical materials within which we comprehend other similar new materials.-

' Exunu I g Benzyl ether derivatives This process may be carried out directly on .the fermented culture media containing the polysaccharide, such as dextran, although the same process can be employed with the extracted dextran after it has been removed from the culture media. This statement applies to the other examples hereinafter recited.

To a portion of the fermented culture medium in which the polysaccharide has been produced and in which there is approximately 30 gm. of the polysaccharide, is added 90 gm. of benzyl chloride and 40 gm. of sodium hydroxide. The resulting mixture is'heated for approximately flve hours. If the temperature is held at 80 to degrees C., the crude product is light orange in color and soft and rubbery in consistency. When higher temperatures of from to degreesC. are employed, an orange-brown product is'obtained of the same consistency but of greater resistance to solvents. The time of heating may range from. 4 to 6 hours but 5 hours is the preferable time. By varying the temperature of this benzylation process, the solubilities in various solvents of the resulting products are varied. These products are substantially insoluble in water.

- Exnlru: II

Butvl ether derivatives To a water solution of the butyl ether derivative is added benzyl chloride and sodium hydroxide in the proportion of 30 gm. or the butyl ether; 90 gm. of benzyl chloride and 40 gm. of sodium hydroxide. The mixture is heated at 80 to 85 degrees C. for a'period of five hours. After removaloi' excess benzyl chloride and benzyl alcoho! by steam distillation, the resulting prodnet is isolated as a rather firm and leathery amorphous mass.

EXAMPLE IV Beta-hydroxy ethyl e her derivatives To a volume of the fermented culture medium containing about 30 gm. of dextran was added 160 gm. of ethylene chlorhydrin and 40 gm. of sodium hydroxide, and the reaction mixture heated at 80 to 85 degrees C. for five hours. At

. the end of this time the solution had become EXAMPLE V Mixed beta-hydroxy ethyl ether-benzyl ether derivatives To a water solution of the beta-hydroxy ethyl ether derivative was added benzyl chloride and sodium hydroxide in the proportion 30 gm. of the ether, 90 gm. of benzyl chloride and 40 gm. of alkali. The mixture was heated at 80 to 85 degrees C. for five hours. After removal of excess benzyl chloride and benzyl alcohol by steam distillation, the resulting product appeared as a golden-brown, rather moist and stringy amorphous mass.

The method of producing the products recited herein is claimed in our co-pending case Ser. No. 156,426, filed July 29, 1937.

It will be understood that we desire to comprehend within this invention such modifications as come within the scope of our claims and our invention. 1

It will be understood that the temperatures and times are relative and may be varied within reasonable limits to secure the objectives desired.

Having thus fully described our invention, what we claim as new anddesire to secure by Letters Patent, is:

1. A benzylether reaction product of dextran, produced by the action of bacteria on sucrose media, andbenzyl chloride, in an alkaline solution.

2. A reaction product of a culture medium containing gummy fermentable polysaccharides of a watersolution of a beta-hydroxy ethyl ether.

of dextran with benzyl chloride and sodium hydroxide.

5. A new composition comprising the benzyl ether of dextran. t

6. A reaction product of dextran comprising a beta-hydroxy ethyl ether derivative of dextran resulting from reacting a fermented culture medium containing dextran in an alkaline solution with ethylene chlorhydrin.

7. A new composition comprising a beta-by droxy ethyl ether derivative of dextran.

8. As a new composition an amorphous betahydroxy ethyl ether derivative of dextran.

9. A process or making ethers of dextran com prising reacting together 30 grams of dextran, 120 grams of an alkyl halide, 40 grams of sodium hydroxide, and enough water to make about a 10% solution of sodium hydroxide.

10. A process of making ethers of dextran comprising adding to 30 grams of dextran, 120 grams of butyl chloride and 40 grams of sodium hydroxide, enough water to produce about a 10% solution of sodium hydroxide, and heating the mixture at 100 C. for about four hours.

11. A process of making an etherified reaction product of dextran comprising heating above room temperature a mixture of dextran and butyl chloride in the proportions of one part of dextran to 4 parts of butyl chloride in about a 10% aqueous solution of sodium hydroxide.

12. A process of making ethers of dextran comprising mixing 3 parts of dextran to 15 parts of ethylene chlorhydrin and 4 parts of sodium hydroxide, together with enough water to get about a 10% solution of sodium hydroxide, heating the mixture from 80 to 85 C. for substantially five hours.

13. A process of making ethers of dextran comprising mixing 3 parts of dextran, 16 parts of ethylene chlorhydrin'and 4 parts, of sodium hydroxide, adding enough water to get about a 10% solution of sodium hydroxide, heating the mixture from 80 to 85 C. for substantially five hours, and isolating the ethyl ether by precipitation with acetone.

14. A new reaction product comprising a mixed hydroxy ethyl ether, benzyl ether derivatives of dextran.

.15. A process of. making ethers of dextran comprising adding to 3 parts of beta-hydroxy ethyl ether of dextran, 9 parts of benzyl chloride and 4 parts of sodium hydroxide, enough water to get about a 10% solution of sodium hydroxide, and heating the mixture from between 80 to 85 C. for substantially five hours.

16. A process of making ethers of dextran comprising adding to 3parts of beta-hydroxy ethyl ether of dextran, 9 parts of benzyl chloride and 4 parts of sodium hydroxide, enough water to get about a 10% solution of sodium hydroxide, and heating the mixture from between 80 to 85 C. for substantially flve hours, removing the excess benzyl chloride and benzyl alcohol by distillation.

1'7. A new product comprising the aralkyl ether derivatives of dextran.

18. A process of making ethers of dextran comprising reacting an aqueous solution of a mixture comprising dextran, aralkyl halide and alkali metal, hydroxide in the relative proportions of approximately 30 grams dextran, 120 grams aralkyl halide and 40 grams sodium hydroxide.

19. A process of making ethers of dextran comprising reacting together 30 grams of dextran, 120 grams of a compound selected from the group consisting of aralkyl halides and chlorhydrins and alkyl halides, 40 grams of sodium hydroxide and enough water to make about a 10% solution of sodium hydroxide.

20. In the process of making ethers of dextran, the step of reactingsubstantially 30 grams dextran and substantially 120 grams of etherifying compound selected from the group consisting of aralkyl and alkyl halides and chlorohydrins together in a 10% aqueous alkali metal solution.

GRANT L. STAHLY. WARNER W. CARLSON. 

